Duplicating machines



ApriI'ZG, 1960 F. s. FRANCIS EIAL 2,93

DUPLICATING MACHINES Filed ma 2?, 195a 25/ A V 7 7 I \ATTORNEY UnitedStates atent I DUPLICATING MACHINES Frederick George Francis, OldSouthgate, London, and Robert James Monlton, Cranham, England, assignorsto Caribonurn Limited, London, England, a company of Great BritainApplication May 27, 1958, Serial No. 738,141

Claims priority, application Great Britain May 29, 1957 2 Claims. (Cl.101-131) The present invention relates to duplicating machines.

Duplicating systems or processes are known in which a reversed positivemaster sheet is prepared by the action of writing upon a sheet of papersuperimposed upon a sheet of carbon paper with its transfer-coated sideupwards. The master sheet is .then used for duplicating by wrapping itround a cylinder which contacts a pressure roller and feeding copysheets between the cylinder and roller. In these duplicating systems, itis common practice for the carbon paper used for preparing the mastersheet to be coated with a transfer composition which includes a highproportion of a dye or other colouring material which is soluble inwater, methylated spirit or some other copying fluid and the duplicatingmachine is provided with arrangements for moistening the copy sheetswith a suitable fluid as they are fed between the cylinder and thepressure roller, so that a portion of the dye on the reversed positivemaster sheet is dissolved and transferred to the copy sheets as anordinary positive copy.

An improvement in duplicating systems of this known kind, which arecornrnonly referred to as spirit duplicating systems, is disclosed inthe co-pending application Serial No. 719,704, filed March 7, 1958, ofF. G. Francis and G. C. Phillpotts wherein the use of methylated spiritor other copying fluid is eliminated and the disadvantages attendantupon the use of sheets bearing quantities of highly coloured and solubledyes are also avoided. Furthermore, with certain papers, methylatedspirit may cause creasing or, if used in excess, can destroy theeffective life of the master copy.

According to the invention disclosed in the aforesaid specification, adry duplicating method comprises the steps of (1) providing a mastersheet having thereon a substantially colourless reversed positive ofwritten matter to be duplicated, the reversed positive comprising acolourless acid-sensitive dyestufi derivative, (2) subjecting the mastersheet to pressure contact with a copy sheet carrying an acid fixingsubstance for forming and then fixing the dyestuii derivative to form anundeveloped copy of the written matter on the copy sheet and (3)thereafter exposing the copy sheet to a source of heat sufficient tocause substantially immediate colour-forming and colourfixing reactionsbetween the colourless dyestuif derivative and the acid fixingsubstance, thereby to form a fixed, legible, developed, positive copy ofthe written matter upon the copy sheet. The colour-forming reaction canoccur in about 1 to 2 seconds or even less, depending upon the intensityof the heating of the copy sheet.

Itis an object of the present invention to provide a duplicating machinefor use in operating a duplicating system of the kind disclosed in theaforesaid application.

According to the present invention, a completely dry duplicating machineconsists essentially of a rotatable cylinder, means for rotating thecylinder, means on the cylinderfor supporting a reversed positive mastersheet in wrapped relationship about the rotatable cylinder for rotationtherewith, the reversed positive master sheet com ice prisingmirror-script written matter to be duplicated constituted by apressure-transferable composition containing a colourless acid-sensitivedyestufi derivative, a pressure roller adjacent the rotatable cylinder,means for driving the pressure roller, copy sheet guide means forguidingcopy sheets between the pressure roller and the rotatable cylinder,thereby to subject the copy sheets successively to pressure contact withthe reversed positive master sheet, each copy sheet carrying on thesurface thereof to be pressure contacted with the reversed positivemaster sheet a non-transferable coating containing an acid fixingsubstance capable of reacting with the dyestuff derivative at anelevated temperature to convert the dyestuff derivative into thedyestufi, the pressure contact of the copy sheets with the reversedpositive master sheet serving to transfer some of thepressure-transferable composition from the master sheet to eachsuccessive copy sheet and also serving to advance each successive copysheet away from the rotatable cylinder and the reversed positive mastersheet, and a source of heat disposed beyond the rotatable cylinder inthe direction of advance of the successive copy sheets for heating eachcopy sheet to an elevated temperature substantially immediately afteritspressure contact with the master sheet thereby to cause a colour-formingreaction to occur between the colourless acid-sensitive dyestuffderivative and the acid fixing substance to form a fixed, legible,developed, positive copy of the written matter upon each successive copysheet in the absence of any means for moistening the copy sheets. I

In order that the invention may be readily understood, certain preferredembodiments are described below by way of example in conjunction withthe accompanying drawing, in which:

Fig. 1 shows a diagrammatic sectional view of one form of dryduplicating machine;

Fig. 2 shows a diagrammatic sectional view of a second form of dryduplicating machine;

Fig. 2a shows a detail of Fig. 2 in side elevational view;

Fig. 3 shows a diagrammatic sectional view of a third formof dryduplicating machine.

Referring to Fig. l, the duplicating machine includes a rotatablecylinder 10 which is mounted for rotation, as by means of a crank handleor an electric motor (not shown), upon a horizontal shaft 11. Thesurface of the cylinder includes means for grip-ping one edge of areversed positive master sheet, of the kind which carries apressuretransferable coating comprising a colourless acid-sensitivedyestuii derivative, as described in the aforesaid application. Thesesheet-gripping means conveniently comprise a hinged or otherwise movableportion 12 of the cylinder surface, which portion 12 can be clamped downupon the edge of the master sheet, which is then wrapped around thesurface of the cylinder 10 so as to be supported thereby, the oppositeedge of the master sheet being left free or secured by suitable means(not shown) in a manner known per se, for instance, in conventionalspirit-duplicating machines. The rotatable cylinder 10 lies above and inpressure contact with a rubber-covered or other resiliently-surfacedpressure roller 14, which is driven by the cylinder 10 on rotation ofthe latter and thereby serves to subject copy sheets to pressure contactwith the master sheet, as the copy sheets are fed to the nip between thecylinder 16 and the roller 14. Due to the pressure and rotation of thecylinder 10, which causes the roller 14 to rotate, the copy sheets arefed towards a pair of rollers, indicated at 15 and 16. The roller 14,which is mounted upon a spindle 14a thus serves both to advance the copysheet through the machine and to bring it into pressure contact with thereversed positive master sheet.

The roller 15 serves as a counterpressure roller for the heatable roller16 and is drivingly coupled with the roller 14, as by means of a belt 33further described'below. The roller 15 thus serves to support andadvance the copy sheet in contact with the roller 16, which contacts theupper surfaceof the copy sheet, namely the surface which was pressedagainst the master sheet. The roller 16 is heated as by means of aninternal electric heating coil indicated at 17 and the heat and pressureto which the copy sheet is then subjected are sufiicient to cause acolour-forming reaction to occur, as described'in more detail in theaforesaid prior application, In this embodiment of the invention, thesource of heat, i.e. the heatable roller 16, raises the temperature ofthe copy sheet by conduction. r

The cylinder 10 and the rollers '14, and 16 are arranged in a suitablehousing 18, which comprises a part enclosing the source of heat and apart'enclosing the rotatable cylinder and may include to this end a baseportion 19, a hinged cover portion 20 over the cylinder 10 and a louvredcover portion 21 over the heating roller 16. The purpose of the louvresin the cover portion 21 is to assist in dissipating heat from themachine The hinged cover portion 20, comprising part of the housing'18enclosing the cylinder 10, is provided so that it can be removed to giveaccess as required'to'the cylinder 10, such as for removing or locatingthe master sheet thereon. The housing 18 is conveniently made generallysymmetrical and includes two opposing side walls, one of which isindicated at 22, uponwhich the cylinder 14), the rollers 14, Hand 16 andother'parts of the machine are conveniently mounted. The machine mayalso include end walls 24 and 25 and the end wall 24 carries a feedplatform 26 for directing'the copy sheet to the nip between the cylinder10 and the roller 14, the platform 26 and the hinged cover portion 20forming between them an inletslot 27 for the copy sheet adjacent thecylinder 14 A copy sheet support 28 is provided between the rollers 15and 14, which are spaced so that the leading edge of the copy sheetreaches the nip between the rollers 15 and 16 as or before the trailingedge leaves the nip be: tween thecylinder 10 and the roller 14. Afurther guide or support platform 29 is provided for receiving the copysheet and directing it to an outlet slot 3% provided in the end wall 25and can lead to a platform 31 on to which the finished, i.e. developed,copy sheets are discharged and collected. A bafiie plate 32 may beprovided above the sheet support 28 to divide the two main parts of themachine housing 18 from one another, to assist in directing hot air tothe louvred cover portion 21 and, especially, 'to=prevent orat'leastdiminish the passage of heat from the heatable roller.16 to the mastersheet. The pair of rollers 15 and 16 are driven in any suitable way, asby means of a driving belt 33 connecting the roller 15 to the roller 14by means of belt pulleys 15a and 14b mounted on the ends thereof,

:as a set of tapes or an endless belt 41, and a super- :posed pressureroller 42, which rollers 40 and '42 feed the "copy sheet on to the upperrun of the tapes or belt 41 towards a roller 44, forming the otherturning point for the endless belt 41, and its superposed pressureroller'45, from where the copy sheet passes to the support platform 29and the outlet slot 30. The pressure roller 42 is preferably made ofindia-rubber and its surface includes a plurality of pointed members,such as the projections 42a, for causing the paper to come into contactwith the copy paper, while coming into contact as little as possiblewith the written matter, so as to avoid undeveloped matter offsetting onthe roller 42.; A copy sheet support 28' is ,provided for guiding thecopy sheet fromthe roller 14 to the conveyor tapes or belt 41, which isdriven in anysuitnumber is not limiting).

able way, as by means of a driving belt or chain 46 connecting theroller 14 to the belt roller 40 in such a manner that the surface speedof the belt 41 is the same as that of the roller 14.

It is found convenient to arrange the resilientpressure roller 14 sothat it can be moved toward-and away from the cylinder 10.- Suflicientfreedom of movement of the roller 14 is provided such that it can betaken out ofcontact with the cylinder 10, when required. This permitsthe master copy to be wrapped round the cylinder 10 in a convenient way,after removal of the hinged'cover portion 20, as by turning the cylinder10 without coming into contact with the roller 14. This is convenientlyprovided for, as shown in Fig. 2a, by mounting the spindle 14a on theroller 14 upon a lever 13 having a cam 13a integral therewith and actingupon the spindle 14a of the roller 14, so as to move the latter towardand away from the cylinder 10 as the lever 13 is pivoted. Thisarrangement also allows the pressure between the roller 14 and thecylinder 10 to be adjusted to suit the particular reversed positivemaster sheet being used;

In this embodiment, the source of heat for causing the colour-formingreaction to occur in the copy sheet while it is upon the endless belt 41operates by radiation and is constituted by one or more 'infra-red'lampsor heaters, shown diagrammatically at 47. If desired, a radiant heatingelement 47a may additionally be located under the belt 41, so as toprovide an additional efiect by convection and/or radiation. For greaterefliciency, the infra-red lamps and/or heaters 47 may be focussed on thecopy sheets, if desired. The heating apparatus may consist of infra-redtubular quartz lamps disposed transversely of the movement of the paper,preferably backed by reflectors. These lamps are conveniently associatedwith a controlling microswitch arranged so that the lamps are onlyenergised when a copy sheet is passing through the machine.

A particularly useful type of heatergwhich may replace that shown inFig. 2, is an open coiled wire heater, which is suitably fenced againstcontact. Eight coils extending across the machine are a suitable number(though this This has the advantage that the machine becomes rapidlyheated to the desired operating temperature. With radiant heating ofthis kind and also with infra-red heating, it is convenient for the baseupon which the paper is carried and also the inside upper surfaces ofthe housing cover to be covered with polished aluminum foil or sheetingor some other heat-reflecting surface, so as to intensify the heatingefiect. It is also an advantage in this embodiment of the invention, toenclose the heater and the transporting surfaces for the copy sheets ina separate shield or cover lower than that shown in the drawing, so thata hot air atmosphere is created under the shield or lower cover throughwhich the copy sheets must pass. e

In a further embodiment, the heating of the copy shee ts is effected bymeans of one or more jets of very hot air which are directed, as bymeans of a fan, ducts and heaters, on to the surface of the copy sheetas it passes through the machine. A suitable temperature for the air isfrom 200 to 350 C.

Referring now to Fig. 3, the cylinder 10 in this embodiment is mountedbeneath its pressure roller, shown at 14', which is enclosed in a fixedportion 20'. of the housing 18' and the housing portion represented bythe end wall, 7

shown at 24, is hinged to the base 19 or is otherwise removable to givethe necessary access to the cylinder 10. As in the embodiment shown inFig. 2, the copy sheet is supported upon an endless conveyorbelt 41driven by means of rollers 40 and 44, which latter roller 44 may itselfbe driven from the cylinder 10 by a driving belt 46'. The source of heatfor heating the copy sheet is provided ,by a hot plate 50 including aradiant electric heating element 51 and mounted above the endless belt41 under the louvred portion 21 of the housing 12.

The mode of operation of the duplicating machine, in any of theembodiments described above, is as follows:

Access to the cylinder it? is obtained by opening the portion 20 or 20'(Fig. 3) of the housing 18 and the master sheet is secured to thecylinder 18 by means of securing arrangements comprising the movableportion 12. The heating means, e.g. the coil 17 (Fig. 1), the infra-redlamps 47 (Fig. 2), the additional heater 47a (Fig. 2) or the coil 51(Fig. 3), are energised and the cylinder is rotated by hand or byoperating an electric or other power drive. Copy sheets are fed to theinlet slot 27, preferably by means of some known form of sheet feedingmechanism, pass through the successive stages of pressure contact withthe master sheet and heating, as previously described, and then emergethrough the outlet slot 30 as clear, fully developed and lighbfastcopies of the written matter to be duplicated.

It will be appreciated that the invention provides a relatively simplemachine for duplicating which may be constructed in a variety ofdifferent forms and operation of which can merely involve energising thesource of heat, wrapping the master sheet round the cylinder androtating a crank handle to feed the acid-coated copy sheets from theinlet slot to the outlet slot. It will also be understood that themachine may be constructed so as to have a mechanical or electric driveand may be provided with driven sheet feeding arrangements.

We claim:

1. A completely dry duplicating machine, which comprises, incombination, a housing divided into a first part and a second part, butwith communication between the first and second housing parts, arotatable cylinder disposed in the first housing part, means forrotating the cylinder, sheet-gripping means on the cylinder forsupporting a reversed positive master sheet in wrapped relationshiparound the surface of the rotatable cylinder for rotation therewith, thereversed positive master sheet comprising rnirror-script written matterto be duplicated constituted by a pressure-transferable coatingcontaining a colourless acid-sensitive dyestufi derivative, a pressureroller disposed in the first housing part adjacent the rotatablecylinder, means disposed in the housing for driving the pressure roller,copy sheet guide means in the first housing part for guiding copy sheetsbetween the pressure roller and the rotatable cylinder thereby tosubject successive copy sheets to pressure contact with the reversedpositive master sheet, each copy sheet carrying on the surface thereofto be pressure contacted with the reversed positive master sheet anon-transferable coating containing an acid fixing substance capable ofreacting with the dyestufi derivative at an elevated temperature toconvert the dyestufi derivative into the dyestufi, the pressure contactof the copy sheets with the reversed positive master sheet serving totransfer some of the pressuretransferable composition from the mastersheet to each successive copy sheet and also serving to advance eachsuccessive copy sheet away from the rotatable cylinder and the reversedpositive master sheet in the first housing part into the second housingpart, a heatable roller disposed in the second housing part beyond therotatable cylinder in the direction of advance of the successive copysheets, means for heating the heatable roller, such roller therebyconstituting a source of heat, another roller disposed in the secondhousing part adjacent to and pressure contactable with the heatableroller and copy sheet guide means disposed between the pressure rollerin the first housing part and the heatable roller in the second housingpart for guiding each successive copy sheet to and between the heatableroller and the roller adjacent thereto for subjecting each copy sheet topressure and simultaneously heating such copy sheet to an elevatedtemperature substantially immediately after its pressure contact withthe master sheet thereby to cause a colourforming reaction to occur onthe copy sheet between the colourless acid-sensitive dyestufl derivativeand the acid fixing substance to form a fixed, legible, developed,positive copy of the written matter upon each successive copy sheetwithout moistening the copy sheets.

2. A completely dry duplicating machine, which comprises, incombination, a housing, a baffle within the housing for dividing it intoa first part and a second part while permitting communication betweenthe first part and the second part, a rotatable cylinder disposed in thefirst housing part, means for rotating the cylinder, sheet-grippingmeans on the cylinder for securing a dry reversed positive master sheetin wrapped relationship around the surface of the rotatable cylinder,the first housing part being constructed in a removable manner so as topermit access to the cylinder for securing the master sheet to therotatable cylinder, an inlet slot in the first housing part forintroducing successive dry copy sheets thereinto, a pressure rollerdisposed in the housing adjacent the rotatable cylinder, means fordriving the pressure roller, copy sheet'guide means disposed in thefirst housing part between the inlet slot and the rotatable cylinder forguiding the dry copy sheets from the inlet slot to and between therotatable cylinder and the pressure roller thereby to subject each copysheet to pressure contact with the reversed positive master sheet, thereversed positive master sheet comprising on the outer surface thereofmirror-script written matter to be duplicated in the dry stateconstituted by a pressure-transferable coating containing a colourlessacid-sensitive dyestufi derivative and each copy sheet carrying on thesurface to be contacted with the reversed positive master sheet anon-transferable coating containing an acid fixing substance adapted toreact with the dyestuft derivative at an elevated temperature to convertthe dyestuff derivative to the dyestufi, the pressure contact of thecopy sheets with the master sheet serving to transfer some of thepressure-transferable composition from the master sheet to eachsuccessive copy sheet and also serving to advance each successive copysheet away from the rotatable cylinder and the reversed positive mastersheet in the first housing part and past the baffle and into the secondhousing part, at least one infra-red lamp constituting a source of heatdisposed in the second housing part beyond the rotatable cylinder in thedirection of advance of the copy sheets, heat-dissipating louvresprovided within the second housing part for dissipating heat from themachine, copy sheet guide means for guiding the copy sheets from therotatable cylinder and into the vicinity of the source of heat wherebyeach successive copy sheet is heated to an elevated temperaturesufficient to cause a colour-forming reaction to occur on such copysheet between the colourless acidsensitive dyestufl derivativepressure-transferred thereto with the pressure-transferable compositionand the acid fixing substance contained in the non-transferable coatingthereon substantially immediately after such pressure contact of eachcopy sheet with the master sheet, thereby to form a fixed, legible,developed, positive copy of the written matter upon each successive copysheet while such copy sheets are maintained continuously dry, an outletslot in the second housing part for the developed copy sheets, and copysheet guide means disposed in the second housing part for guiding thedeveloped copy sheets from the vicinity of the source of heat to theoutlet slot.

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